TeV γ-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0 with H.E.S.S

• Published in: Monthly notices of the Royal Astronomical Society 2014-06, Vol.441 (1), p.790-799
• Main Authors: Benkhali, F. Ait, Anton, G., Barnacka, A., Tjus, J. Becker, Bernlöhr, K., Bissaldi, E., Böttcher, M., Boisson, C., Bolmont, J., Brucker, J., Brun, F., Bulik, T., Cerruti, M., Chadwick, P.M., Cheesebrough, A., Chrétien, M., Colafrancesco, S., Couturier, C., Deil, C., deWilt, P., Dickinson, H. J., Djannati-Ataï, A., Dutson, K., Dyks, J., Dyrda, M., Eger, P., Espigat, P., Fernandes, M. V., Fontaine, G., Füßling, M., Gajdus, M., Garrigoux, T., Giebels, B., Glicenstein, J.F., Grondin, M.-H., Grudzińska, M., Hahn, J., Heinzelmann, G., Henri, G., Hervet, O., Holler, M., Horns, D., Jacholkowska, A., Jahn, C., Janiak, M., Kastendieck, M.A., Kaufmann, S., Khélifi, B., Kieffer, M., Klepser, S., Klochkov, D., Krakau, S., Krayzel, F., Laffon, H., Lopatin, A., Lu, C.-C., Menzler, U., Moulin, E., Murach, T., de Naurois, M., Niemiec, J., Nolan, S.J., Ohm, S., Ostrowski, M., Oya, I., Parsons, R. D., Pekeur, N. W., Pelletier, G., Raue, M., Reimer, A., Renaud, M., Rowell, G., Rulten, C.B., Sahakian, V., Schwanke, U., Steenkamp, R., Stegmann, C., Stycz, K., Sushch, I., Terrier, R., Tluczykont, M., Valerius, K., van Eldik, C., van Soelen, B., Vasileiadis, G., Viana, A., Vincent, P., Vorster, M., Vuillaume, T., Wagner, S. J., Ward, M., Weidinger, M., Weitzel, Q., Willmann, P., Wörnlein, A., Wouters, D., Zabalza, V., Zdziarski, A. A., Zech, A., Zechlin, H.-S.
• Format: Article
• Language: English
• Subjects: Astroparticle Physics; Astropartikelfysik; Astrophysics; gamma-rays: ISM; High Energy Astrophysical Phenomena; ISM: individual objects: SNR G1.9+0.3; ISM: individual objects: SNR G330.2+1.0; ISM: magnetic fields; ISM: supernova remnants; Physics; radiation mechanisms: non-thermal; Sciences of the Universe
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stu459

The non-thermal nature of the X-ray emission from the shell-type supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0 is an indication of intense particle acceleration in the shock fronts of both objects. This suggests that the SNRs are prime candidates for very-high-energy (VHE; E > 0.1 TeV) γ-ray observations. G1.9+0.3, recently established as the youngest known SNR in the Galaxy, also offers a unique opportunity to study the earliest stages of SNR evolution in the VHE domain. The purpose of this work is to probe the level of VHE γ-ray emission from both SNRs and use this to constrain their physical properties. Observations were conducted with the H.E.S.S. (High Energy Stereoscopic System) Cherenkov Telescope Array over a more than six-year period spanning 2004–2010. The obtained data have effective livetimes of 67 h for G1.9+0.3 and 16 h for G330.2+1.0. The data are analysed in the context of the multiwavelength observations currently available and in the framework of both leptonic and hadronic particle acceleration scenarios. No significant γ-ray signal from G1.9+0.3 or G330.2+1.0 was detected. Upper limits (99 per cent confidence level) to the TeV flux from G1.9+0.3 and G330.2+1.0 for the assumed spectral index Γ = 2.5 were set at 5.6 × 10−13 cm−2 s−1 above 0.26 TeV and 3.2 × 10−12 cm−2 s−1 above 0.38 TeV, respectively. In a one-zone leptonic scenario, these upper limits imply lower limits on the interior magnetic field to B G1.9 ≳ 12 μG for G1.9+0.3 and to B G330 ≳ 8 μG for G330.2+1.0. In a hadronic scenario, the low ambient densities and the large distances to the SNRs result in very low predicted fluxes, for which the H.E.S.S. upper limits are not constraining.